GB530854A - Improvements in and relating to fuse-switches - Google Patents

Abstract

530,854. Snap-action switches. DORMAN & SMITH, Ltd., and SMALLEY, T. June 24, 1939, No. 18444. [Class 38 (v)] An enclosed fuse-switch is locked in both the closed and open positions by a spring-pressed bolt 20 on a movable part 15 of the mechanism engaging one of two holes in the side of the box ; this bolt is withdrawn by the normal movement of the operating lever but the withdrawing movement is prevented when the box cover is removed; interlocking mechanism 17, 18 also prevents the cover being removed when the switch is closed. The movable contacts of the switch (not shown) are carried by a frame 13 which is given a parallel movement by links 15 pivoted to the frame at 14 and to fixed points 7. The upper link 15, which is a U-shaped member carries the bolt 20 and has the extension 17 which overlaps the hook 18 on the cover 19 to prevent removal of the latter when the switch is closed. The operating lever, which is outside the switch-box, rotates about the upper axis 7 and drives a member 8 pivoted to a rod 22, 23 which passes through a block 24 and is surrounded by a compression spring 26. The block 24 is pivoted to an extension of link 15 and when the member 8 is rotated by the handle, the rod 22, 23 tilts, the spring 26 becomes compressed and tends to rotate the link 15. Movement is however prevented by the bolt 20 till a bevelled edge 9 on the member 8 presses back a cone-shaped portion of the bolt 20. When the lid is removed, a plate 28 which normally rests at 30 against the hook 18 moves to the right under the action of a spring 29 so as to come behind a portion of the bolt 20 and prevents its withdrawal.